Lightning arresters in the form of metal oxide varistor discs are used to protect electrical equipment and personnel from overvoltage surges usually caused by lightning. The varistors are arranged within electrically-insulative enclosures in a stacked array to provide an electrical series circuit whereby the clamping voltage of the arrester is determined by the series addition of the individual varistor clamping voltages.
To provide good electrical connection between the varistors within the stacked array, the varistors are often bound together by polymer filaments prior to insertion within the enclosures and compression springs are positioned at one or both ends to provide compressive forces to the varistors to insure good electrical connection. Spring washers and the like are also positioned between the varistors to provide additional compressive forces for enhanced electrical connection. U.S. Pat. Nos. 4,656,555 and 4,864,456 describe the use of filament windings and compression springs to improve electrical connection between the varistors per se as well as between the varistors and the arrester end terminals.
The use of such springs, washers and filaments add to the manufacturing complexity and costs since some time and material is involved in the winding and installation processes. It would be economically advantageous to provide good electrical connection between the varistors themselves as well as between the varistors and the arrester end terminals without requiring any such filaments, springs or washers.
One purpose of the invention is to provide a lightning arrester having excellent electrical continuity between the varistors in a stacked array and between the varistors and the end terminals of the arrester without requiring additional compressive devices.